(a) Field of the Invention
An optical fingerprint recognition sensor is provided.
(b) Description of the Related Art
Recently, a capacitive fingerprint sensor and an optical fingerprint sensor have been widely used. In general, the capacitive fingerprint sensor recognizes a fingerprint by sensing static electricity caused by the fingerprint of a human body using a semiconductor element that is sensitive to a voltage and a current. On the contrary, the optical fingerprint sensor has excellent durability, and is formed with a structure that includes a light source and an optical sensor and thus the optical fingerprint sensor senses a user's fingerprint when the optical sensor senses light emitted from the light source.
A conventional optical fingerprint sensor may not be able to acquire a clear image of a fingerprint due to incident external light such as sunlight.
In addition, when the fingerprint and a surface of the sensor are too far from each other, light reflected from an adjacent fingerprint can be easily incident thereon, and thus when the distance between the fingerprint and the surface of the sensor is 10 um or more, light reflected from fingerprints are mixed so that a clear fingerprint image cannot be acquired.
Further, light utilization efficiency (energy utilization efficiency) of the backlight used for sensor recognition is low, thereby deteriorating productivity.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.